C5 Z06 180 degree header build thread
 

I should start with an explanation of what 180 degree headers are to those who are not familiar with them. We all know that muscle car sound, as awesome as it may be it is created by uneven exhaust pulses through the collectors of typical American V8 engines, for that matter all American V8s except for the Latest Mustang GT350 and GT350R which use a flat plane crankshaft. If you look at the firing order of an LS for example, 18726543, you can see there are double stacked pulses in one bank as a pulse is skipped in the opposing bank. This gives the rumble we are all familiar with. By rearranging the primary header pipes in the collectors, 180 degree headers can space the exhaust pulses in even increments. This changes the sound to that of exotic flat plane crankshaft V8s. To make this happen, two primaries from one bank share the same collector as two primaries from the opposing bank. And the other two from each bank enter into the other collector. In all V8s I am familiar with, it is the center two from one bank and the outer two from the other bank in one collector and vice versa. Due to having to have four of the primary pipes cross sides, packaging 180 degree headers is impossible in most cars unless the primaries are made to a length way longer than optimal. Unless the engine is rear mounted or you can completely ditch the passenger seat, there is no option for 180 degree headers.

Exhaust note, in many cases is more important to me than what a car looks like. Graciously sculpted panels and the perfectly detailed paint applied to them can certainly entertain my eyes for hours. But when the ignition switch is turned and the pipes fire off with a harmony that pleases the ears, that's when the true appreciation of an automotive creation wins my heart.

I first heard the exotic music of 180 degree headers at of all places, the redneck festival that was Columbus Motor Speedway. There was a single late model stock car in a field of 20 or so racing in the A main feature race rocking the pipes that transformed the muscle of the small block Chevrolet under it's hood into a symphony of audible perfection. I took notice and never forgot that wonderful noise. 25 years later I built a set of 180 degree headers for my Howe TA2 chassis. It was not the easy route but it was possible so it had to be done. I had to have that sound for myself!

Well, photobucket has decided to be complete dicks and no longer allow 3rd party linking unless a "ransom" of $400 is paid. So all of the photos of this build thread can no longer be viewed in the thread along with the descriptions until I move everything to a new host. To be honest, I don't know if I will ever find time to do so. For now, here is a link to my photobucket library where all the pictures that were once in this thread can be found, http://s157.photobucket.com/user/tinman_015/library/

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Now, I have a C5 Z06 in my possession. Because the transmission is located at the rear, I figured I could make the same thing happen in but under it. Without a transmission in the way, the collectors could be placed where it typically is found in most cars.

I decided to use 1 3/4" primaries due to tight packaging and my target primary length is 38". Longer than most headers but this will be a road course car and torque out of the corner is more important than dyno numbers. First step, locate the collectors in the tunnel. I made a little jig that allowed me to slide them fore and aft to get all the tubes where they need to go yet keep them as short as possible, 38" is a long way when crossing side to side.

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How much time have you spent under your Z? I'd be seriously impressed if you can make 180deg headers to fit in a C5.
I'd like to hear a clip of an LS motor with 180deg headers also...

I live in Ohio, so it's been on the lift for a few weeks now awaiting better weather.

Stay tuned, I'm determined to make this happen. Sound clips shall happen come spring.

To make as much room as possible, I ground the bellhousing cover exhaust bracket bosses off and countersunk the mounting bolt holes and used flathead allen bolts from https://www.mcmaster.com/#

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Next step, driver side primary routing. Cylinders 1,3,5,and 7 will enter the top of the collectors. 1 and 7 on the driver side and 3 and 5 into the passenger side. Afterwards the passenger side cylinders will enter the collectors. 4 and 6 to the driver side and 2 and 8 into the passenger side.

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Damn! Failure #1. With this configuration the #3 primary length can not be kept at 38"... Version 1.2 to follow.

But can you take it apart?
LOL!

J/k - that looks like some SERIOUS work.... anything gonna be different with the axle back?

The collectors are slip fit and will get bolt or spring tabs welded on to keep it all together.

I plan to run the factory TI mufflers at least at first. Might make a pair of race pipes for the track as well. In between will be an x pipe of some sort. I have 4 ideas I want to try so they will be made from mild steel and the one that produces the best sound will then be duplicated in stainless.

Ever heard long tubes ran into a single flange?

Sir, I am not worthy to sweep out your garage.
This boggles my mind. The thread without pictures would be difficult to truly understand.
As you said: Someone had to do it. Why NOT you?

Thanks for sharing.

Yes, very evil sounding as well. But unfortunately an 8 into 1 collector would be far to tall to fit in the tunnel of the C5.

Perhaps.

On this car, most cheep long tube heads fit into the tunnel any way.
If you find ones that have the tubes are on the inside then half of your work is already done. easy peasy. Cross those, or make a single manifold design.

It will simplify everything and eliminate the need for a cross pipe.

A mid engine car where you can get a bit of exhaust scavenging (perhaps)?

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Are you running O2's? Will they work that far back in the exhaust?

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At this point all four driver side primaries are past the pinch point and left long, trimming will be done tube by tube as they make their way towards the header flange. The bottom of the #5 tube will end up around 1/2" below the oil pan which does bother me but I knew concessions would need to be made to make it happen.

I will be running O2 sensors and will need extended harnesses but as long as they are in the collector, they should be fine.

On the O2 sensor note, I'm guessing there will be issues do to the bank 1 sensor will now be reading cylinders 1,4,6,and 7 and bank 2 will be reading cylinders 2,3,5,and 8. I'm in no way a tuner but have read that through HPtuners, the banks can be assigned with different cylinders, fingers crossed, this holds true. If any tuners happening to be reading this could chime in, it would be much appreciated.

WOW!!!

:cheers:



I don't know if it would be at all helpful to your efforts, but as you already know, "packaging" is a huge effort, for a 180* exhaust system. NASCAR rules require an "under car" exhaust, so their packaging issues are similar to yours. My point is that a few years back, when Morgan-McClure Racing was running the Kodak colors, I believe they were pioneers, sort of, with 180* headers. If you can find pictures of one of their cars from that era, it might help you.

:lurk:

A good friend of mine and I were discussing that Sterling Marlin driven Daytona entry earlier. It would be very interesting to find some underside pictures of that car. I'm guessing back then the engines did not sit as low in the chassis and that might be around the time they started running dry sump oil systems. This would have allowed them to cross the primaries under the shallow dry sump pan. All speculation on my part. Anyone have info on that car?